/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/
let a = new Promise((resolve, reject) => {
  setTimeout(()=>{
    resolve('hello')
  },10)
})
let b = new Promise((resolve, reject) => {
  setTimeout(()=>{
    resolve('lagou')
  },10)
})
let c = new Promise((resolve, reject) => {
  setTimeout(()=>{
    resolve('I ♥ U')
  },10)
})

Promise.all([a,b,c]).then(value=>console.log(value.join(' ')));